var WebRtcStreamer = (function () {

	/** 
	 * Interface with WebRTC-streamer API
	 * @constructor
	 * @param {string} videoElement - id of the video element tag
	 * @param {string} srvurl -  url of webrtc-streamer (default is current location)
	 */
	var WebRtcStreamer = function WebRtcStreamer(videoElement, srvurl) {
		if (typeof videoElement === "string") {
			this.videoElement = document.getElementById(videoElement);
		} else {
			this.videoElement = videoElement;
		}
		this.srvurl = srvurl || location.protocol + "//" + window.location.hostname + ":" + window.location.port;
		this.pc = null;

		this.pcOptions = {
			"optional": [{
				"DtlsSrtpKeyAgreement": true
			}]
		};

		this.mediaConstraints = {
			offerToReceiveAudio: true,
			offerToReceiveVideo: true
		};

		this.iceServers = null;
		this.earlyCandidates = [];
	}

	WebRtcStreamer.prototype._handleHttpErrors = function (response) {
		if (!response.ok) {
			throw Error(response.statusText);
		}
		return response;
	}

	/** 
	 * Connect a WebRTC Stream to videoElement 
	 * @param {string} videourl - id of WebRTC video stream
	 * @param {string} audiourl - id of WebRTC audio stream
	 * @param {string} options -  options of WebRTC call
	 * @param {string} stream  -  local stream to send
	 */
	WebRtcStreamer.prototype.connect = function (videourl, audiourl, options, localstream) {
		this.disconnect();

		// getIceServers is not already received 未接收到getIce服务器
		if (!this.iceServers) {
			console.log("Get IceServers");

			fetch(this.srvurl + "/api/getIceServers")
				.then(this._handleHttpErrors)
				.then((response) => (response.json()))
				.then((response) => this.onReceiveGetIceServers.call(this, response, videourl, audiourl, options, localstream))
				.catch((error) => this.onError("getIceServers " + error))

		} else {
			this.onReceiveGetIceServers(this.iceServers, videourl, audiourl, options, localstream);
		}
	}

	/** 
	 * Disconnect a WebRTC Stream and clear videoElement source
	 */
	WebRtcStreamer.prototype.disconnect = function () {
		if (this.videoElement) {
			this.videoElement.src = "";
		}
		if (this.pc) {
			fetch(this.srvurl + "/api/hangup?peerid=" + this.pc.peerid)
				.then(this._handleHttpErrors)
				.catch((error) => this.onError("hangup " + error))


			try {
				this.pc.close();
			} catch (e) {
				console.log("Failure close peer connection:" + e);
			}
			this.pc = null;
		}
	}

	/*
	 * GetIceServers callback
	 */
	WebRtcStreamer.prototype.onReceiveGetIceServers = function (iceServers, videourl, audiourl, options, stream) {
		this.iceServers = iceServers;
		this.pcConfig = iceServers || {
			"iceServers": []
		};
		try {
			this.createPeerConnection();

			var callurl = this.srvurl + "/api/call?peerid=" + this.pc.peerid + "&url=" + encodeURIComponent(videourl);
			if (audiourl) {
				callurl += "&audiourl=" + encodeURIComponent(audiourl);
			}
			if (options) {
				callurl += "&options=" + encodeURIComponent(options);
			}

			if (stream) {
				this.pc.addStream(stream);
			}

			// clear early candidates
			this.earlyCandidates.length = 0;

			// create Offer
			var bind = this;
			this.pc.createOffer(this.mediaConstraints).then(function (sessionDescription) {
				console.log("Create offer:" + JSON.stringify(sessionDescription));

				bind.pc.setLocalDescription(sessionDescription, function () {
					fetch(callurl, {
							method: "POST",
							body: JSON.stringify(sessionDescription)
						})
						.then(bind._handleHttpErrors)
						.then((response) => (response.json()))
						.catch((error) => bind.onError("call " + error))
						.then((response) => bind.onReceiveCall.call(bind, response))
						.catch((error) => bind.onError("call " + error))

				}, function (error) {
					console.log("setLocalDescription error:" + JSON.stringify(error));
				});

			}, function (error) {
				alert("Create offer error:" + JSON.stringify(error));
			});

		} catch (e) {
			this.disconnect();
			alert("connect error: " + e);
		}
	}


	WebRtcStreamer.prototype.getIceCandidate = function () {
		fetch(this.srvurl + "/api/getIceCandidate?peerid=" + this.pc.peerid)
			.then(this._handleHttpErrors)
			.then((response) => (response.json()))
			.then((response) => this.onReceiveCandidate.call(this, response))
			.catch((error) => this.bind.onError("getIceCandidate " + error)) // .0.0
	}

	/*
	 * create RTCPeerConnection 
	 */
	WebRtcStreamer.prototype.createPeerConnection = function () {
		console.log("createPeerConnection  config: " + JSON.stringify(this.pcConfig) + " option:" + JSON.stringify(this.pcOptions));
		this.pc = new RTCPeerConnection(this.pcConfig, this.pcOptions);
		var pc = this.pc;
		pc.peerid = Math.random();

		var bind = this;
		pc.onicecandidate = function (evt) {
			bind.onIceCandidate.call(bind, evt);
		};
		pc.onaddstream = function (evt) {
			bind.onAddStream.call(bind, evt);
		};
		pc.oniceconnectionstatechange = function (evt) {
			console.log(evt);
			console.log("oniceconnectionstatechange  state: " + pc.iceConnectionState);
			if (bind.videoElement) {
				if (pc.iceConnectionState === "connected") {
					bind.videoElement.style.opacity = "1.0";
				} else if (pc.iceConnectionState === "disconnected") {
					bind.videoElement.style.opacity = "0.25";
				} else if ((pc.iceConnectionState === "failed") || (pc.iceConnectionState === "closed")) {
					bind.videoElement.style.opacity = "0.5";
				} else if (pc.iceConnectionState === "new") {
					bind.getIceCandidate.call(bind)
				}
			}
		}
		pc.ondatachannel = function (evt) {
			console.log("remote datachannel created:" + JSON.stringify(evt));

			evt.channel.onopen = function () {
				console.log("remote datachannel open");
				this.send("remote channel openned");
			}
			evt.channel.onmessage = function (event) {
				console.log("remote datachannel recv:" + JSON.stringify(event.data));
			}
		}
		pc.onicegatheringstatechange = function () {
			if (pc.iceGatheringState === "complete") {
				const recvs = pc.getReceivers();

				recvs.forEach((recv) => {
					if (recv.track && recv.track.kind === "video") {
						console.log("codecs:" + JSON.stringify(recv.getParameters().codecs))
					}
				});
			}
		}

		try {
			var dataChannel = pc.createDataChannel("ClientDataChannel");
			dataChannel.onopen = function () {
				console.log("local datachannel open");
				this.send("local channel openned");
			}
			dataChannel.onmessage = function (evt) {
				console.log("local datachannel recv:" + JSON.stringify(evt.data));
			}
		} catch (e) {
			console.log("Cannor create datachannel error: " + e);
		}

		console.log("Created RTCPeerConnnection with config: " + JSON.stringify(this.pcConfig) + "option:" + JSON.stringify(this.pcOptions));
		return pc;
	}


	/*
	 * RTCPeerConnection IceCandidate callback
	 */
	WebRtcStreamer.prototype.onIceCandidate = function (event) {
		if (event.candidate) {
			if (this.pc.currentRemoteDescription) {
				this.addIceCandidate(this.pc.peerid, event.candidate);
			} else {
				this.earlyCandidates.push(event.candidate);
			}
		} else {
			console.log("End of candidates.");
		}
	}


	WebRtcStreamer.prototype.addIceCandidate = function (peerid, candidate) {
		fetch(this.srvurl + "/api/addIceCandidate?peerid=" + peerid, {
				method: "POST",
				body: JSON.stringify(candidate)
			})
			.then(this._handleHttpErrors)
			.then((response) => (response.json()))
			.then((response) => {
				console.log("addIceCandidate ok:" + response)
			})
			.catch((error) => this.onError("addIceCandidate " + error))
	}

	/*
	 * RTCPeerConnection AddTrack callback
	 */
	WebRtcStreamer.prototype.onAddStream = function (event) {
		console.log("Remote track added:" + JSON.stringify(event));

		this.videoElement.srcObject = event.stream;
		var promise = this.videoElement.play();
		if (promise !== undefined) {
			var bind = this;
			promise.catch(function (error) {
				console.warn("error:" + error);
				bind.videoElement.setAttribute("controls", true);
			});
		}
	}

	/*
	 * AJAX /call callback
	 */
	WebRtcStreamer.prototype.onReceiveCall = function (dataJson) {
		var bind = this;
		console.log("offer: " + JSON.stringify(dataJson));
		var descr = new RTCSessionDescription(dataJson);
		this.pc.setRemoteDescription(descr, function () {
			console.log("setRemoteDescription ok");
			while (bind.earlyCandidates.length) {
				var candidate = bind.earlyCandidates.shift();
				bind.addIceCandidate.call(bind, bind.pc.peerid, candidate);
			}

			bind.getIceCandidate.call(bind)
		}, function (error) {
			console.log("setRemoteDescription error:" + JSON.stringify(error));
		});
	}

	/*
	 * AJAX /getIceCandidate callback
	 */
	WebRtcStreamer.prototype.onReceiveCandidate = function (dataJson) {
		console.log("candidate: " + JSON.stringify(dataJson));
		if (dataJson) {
			for (var i = 0; i < dataJson.length; i++) {
				var candidate = new RTCIceCandidate(dataJson[i]);

				console.log("Adding ICE candidate :" + JSON.stringify(candidate));
				this.pc.addIceCandidate(candidate, function () {
					console.log("addIceCandidate OK");
				}, function (error) {
					console.log("addIceCandidate error:" + JSON.stringify(error));
				});
			}
			this.pc.addIceCandidate();
		}
	}


	/*
	 * AJAX callback for Error
	 */
	WebRtcStreamer.prototype.onError = function (status) {
		console.log("onError:" + status);
	}

	return WebRtcStreamer;
})();

if (typeof module !== 'undefined' && typeof module.exports !== 'undefined')
	module.exports = WebRtcStreamer;
else
	window.WebRtcStreamer = WebRtcStreamer;